Now, the first entry in tables is either a valid DTE/ITE or a dummy
entry pointing to the first valid DTE/ITE. Revise the DTE/ITE restore
process to utilize the dummy entry to avoid unnecessary (erroneous)
entry scanning.
This is not supposed to break the ITS table ABI REV0.
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
arch/arm64/kvm/vgic/vgic-its.c | 46 ++++++++++++++++++++++++++--------
1 file changed, 35 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 867cc5d3521d..e07939613f5c 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -2129,23 +2129,30 @@ static int vgic_its_restore_ite(struct vgic_its *its, u32 event_id,
u32 coll_id, lpi_id;
struct its_ite *ite;
u32 offset;
+ u32 magic;
val = *p;
val = le64_to_cpu(val);
- coll_id = val & KVM_ITS_ITE_ICID_MASK;
lpi_id = (val & KVM_ITS_ITE_PINTID_MASK) >> KVM_ITS_ITE_PINTID_SHIFT;
- if (!lpi_id)
- return event_id + 1; /* invalid entry, no choice but to scan next entry */
+ offset = val >> KVM_ITS_ITE_NEXT_SHIFT;
+ if (event_id + offset >= BIT_ULL(dev->num_eventid_bits))
+ return -EINVAL;
+
+ if (!lpi_id) {
+ magic = (val & KVM_ITS_ENTRY_DUMMY_MASK) >> KVM_ITS_ENTRY_DUMMY_SHIFT;
+ if (magic != KVM_ITS_ENTRY_DUMMY_MAGIC)
+ offset = 1;
+
+ return event_id + offset;
+ }
if (lpi_id < VGIC_MIN_LPI)
return -EINVAL;
- offset = val >> KVM_ITS_ITE_NEXT_SHIFT;
- if (event_id + offset >= BIT_ULL(dev->num_eventid_bits))
- return -EINVAL;
+ coll_id = val & KVM_ITS_ITE_ICID_MASK;
collection = find_collection(its, coll_id);
if (!collection)
@@ -2303,17 +2310,30 @@ static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
u64 entry = *(u64 *)ptr;
bool valid;
u32 offset;
+ u32 magic;
int ret;
entry = le64_to_cpu(entry);
valid = entry >> KVM_ITS_DTE_VALID_SHIFT;
- num_eventid_bits = (entry & KVM_ITS_DTE_SIZE_MASK) + 1;
- itt_addr = ((entry & KVM_ITS_DTE_ITTADDR_MASK)
- >> KVM_ITS_DTE_ITTADDR_SHIFT) << 8;
- if (!valid)
- return id + 1;
+ /*
+ * Since we created a dummy head entry for the DTE static linked list in
+ * the table if necessary, no need to scan to find the list head.
+ * But if the saved table was done without dummy entry support, we still
+ * have to scan one by one.
+ */
+ if (!valid) {
+ magic = (entry & KVM_ITS_ENTRY_DUMMY_MASK) >>
+ KVM_ITS_ENTRY_DUMMY_SHIFT;
+ if (magic != KVM_ITS_ENTRY_DUMMY_MAGIC)
+ offset = 1;
+ else
+ offset = (entry & KVM_ITS_DTE_DUMMY_NEXT_MASK) >>
+ KVM_ITS_DTE_DUMMY_NEXT_SHIFT;
+
+ return id + offset;
+ }
/* dte entry is valid */
offset = (entry & KVM_ITS_DTE_NEXT_MASK) >> KVM_ITS_DTE_NEXT_SHIFT;
@@ -2321,6 +2341,10 @@ static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
if (!vgic_its_check_id(its, baser, id, NULL))
return -EINVAL;
+ num_eventid_bits = (entry & KVM_ITS_DTE_SIZE_MASK) + 1;
+ itt_addr = ((entry & KVM_ITS_DTE_ITTADDR_MASK)
+ >> KVM_ITS_DTE_ITTADDR_SHIFT) << 8;
+
dev = vgic_its_alloc_device(its, id, itt_addr, num_eventid_bits);
if (IS_ERR(dev))
return PTR_ERR(dev);
--
2.47.0.199.ga7371fff76-goog
